The present invention relates to a bone screw for screwing into a bone. The present invention further relates to an osteosynthesis device for fixing at least two bone parts relative to one another in a fixation position, comprising at least two bone screws and a carrier element fastenable to at least two of the at least two bone screws. The present invention further relates to a method of manufacturing a bone screw.
Known internal fixation devices comprise bone screws that usually carry a screw head, to which a carrier element is fastenable. Such internal fixation devices are used, for example, to fasten two vertebrae of a human spinal column relative to one another, either because an adjacent vertebra is damaged or because a disk connecting the two vertebrae is damaged. In order to ensure as good a hold of the bone screw in the bone as possible, preferably bone screws with as large an external thread diameter as possible are used.
Bone screws are further known, which have a screw head that is movable relative to the screw body of the bone screw. The screw head may be, for example, polyaxially pivotable. In this case, the bone screw cannot be manufactured in one piece but is composed of substantially two parts, namely the screw body and the screw head. For connecting the two parts, in known bone screws the screw head is passed through an opening of the screw head. A maximum outside diameter of the screw body is therefore defined by the inside diameter of the opening.
As the screw head generally projects from the bone, it is desirable to provide particularly small screw heads. However, the size of the screw bodies to be connected to the screw heads may be reduced only to a qualified extent because otherwise it is impossible to guarantee a secure hold of the screw body in the bone.